Giant squid invade California waters

A mysterious sea creature, more than 2 metres long, weighing up to 45 kg. It hunts in packs of hundreds, flying through the water at 40 kilometres an hour, changing colour.

With a parrot-like beak and arms covered with thousands of sharp barbs, it attacks and tries to eat nearly anything it sees, including fish, scuba divers, even its own kind.

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But it's not a creature of Hollywood. It's real. And it's reached the Monterey Bay. The Humboldt squid, also known as the giant squid or jumbo squid, traditionally has lived in warm waters off South America and Mexico, where fishermen call it "diablo rojo," or "red devil."

For reasons that still aren't entirely clear, large numbers of the scrappy cephalopods have been steadily expanding their range north, first off San Diego and Los Angeles, where hundreds have washed up on beaches in recent years.

Now they appear to have taken up residence in Monterey Bay, according to a study released recently by researchers from Stanford University and the Monterey Bay Aquarium Research Institute (MBARI), using more than 16 years of underwater video.

"These are aggressive, pugnacious bullies," said Bruce Robison, senior scientist at MBARI, based in Moss Landing, California. "They are a sight to behold."

The invasion has sparked the interest of recreational fishermen, who fight to land them like marlins. It has piqued the curiosity of some chefs, who say they can be cooked like calamari. And it has drawn wary attention from fisheries biologists, who are concerned that the voracious invertebrates could deplete commercial fisheries like hake, known as Pacific whiting, a common ingredient in frozen fish sticks, or rockfish, which are sold in restaurants as red snapper.

"When it moves into an area, it can potentially have drastic impacts," said Louis Zeidberg, a post-doctoral researcher at Stanford's Hopkins Marine Station in Pacific Grove, California. "We've yet to see how that is going to play out, but it could change things."

"This is like the creature from the black lagoon. They are very strange looking," he said with a chuckle. "Nobody here has ever caught anything like this.

"They fight so much, they are a real bear to pull in," he added. "I've seen big heavy construction workers after catching two or three look like they've been worked over by a prize fighter."

Zeidberg and Robison concluded that the Humboldt squid have become a permanent presence in Monterey Bay since about 2002. They published their findings in Proceedings of the National Academy of Sciences, a scientific journal.

The duo reviewed video footage that Robison and other researchers shot around Monterey Bay from more than 3,000 dives with unmanned submersibles back to 1991.

They didn't see any Humboldt squid until 1997. Then, during an El Nino year - when Pacific waters warm and currents change - they noticed some, but the animals disappeared. There were only one or two a year spotted until 2002, another mild El Nino year. But after that, the squid, which live to be only one or two years old, were seen on almost every dive.

Because the squid dive as deep as 915 metres and have been filmed hunting krill, lanternfishes, hake and other animals in a wide temperature range, Robison and Zeidberg say they don't think global warming or other temperature changes are driving the expansion.

Instead, they suspect that the squid's range has expanded because fishing has reduced the populations of predators such as large tuna, marlins and swordfish that eat them in their natural range off South America. Similarly, some smaller species of tuna, which compete with squid for food, also have been reduced.

"It's an indication that looking at the entire Pacific Ocean, things are out of whack," said Zeidberg.

"You've got this sort of weird species spreading out into areas that it has never really taken up residence before," he said. "It's an indication the overall health of the ocean is not as good as it should be. We need to figure out exactly what is causing this range expansion, and find some kind of political or economic solution."

The Humboldt squid is named after an ocean current off South America that was documented by naturalist Alexander von Humboldt. Known by their Latin name Dosidicus gigas, Humboldt squid are roughly six times the size of common market squid, Loligo opalescens, a smaller species commonly found off the California coast and sold as calamari.

Zeidberg said some restaurants have begun to put Humboldt squid on the menu.

"A lot of people find it kind of tough and kind of gamy compared to traditional calamari, but I like it," he said.

"They make big steaks out of them."

The squid are not to be confused with a species of giant squid known as Architeuthis that can grow up to 18 metres. Those are the stuff of 20,000 Leagues Under the Sea and other fantastic stories. Last year, for the first time, a 9 metre giant squid was filmed off Japan.

Humboldt squid have attacked divers filming documentaries in Mexico, dislocating the shoulder and tearing the wetsuit of one. So do California divers and swimmers need to worry?

"I don't really think they are going to want to get into the water where people are," Zeidberg said, noting their deep-water habits. "It doesn't seem like there's enough food for them, and that's not their normal habitat."

But, he said, they sure can get imaginations racing.

"It's not a coincidence," he joked, "that a lot of the space aliens in movies do seem to look like squid."